Craving and binge drinking are behaviors in alcoholism that are thought to be mediated in part by neuroadaptations in brain regions related to reward and motivation. Locomotor sensitization is an increased response to repeated doses of a drug and this behavior has been shown to involve gene expression changes in these same brain regions. Therefore, the long-term goal of this proposal is to identify potential molecular mechanisms underlying behaviors related to alcoholism by microarray analysis of reward-related brain regions in mice sensitized to ethanol. This will be accomplished by fulfilling two specific aims. Specific Aim 1: Characterize gene expression changes both during acute ethanol responses and at basal levels in mice sensitized to ethanol. Mice will receive daily injections of saline, ethanol for two weeks with locomotor activation recorded on days three and fourteen. Mice will be sacrificed four hours or several days after the final treatment for array analysis to compare acute expression changes to basal-level changes. Specific Aim 2: Further correlate expression changes with behavior using mouse strains differing in sensitization development.